Nomadik GPIO controller

Required properties:
- compatible            : Should be "st,nomadik-gpio".
- reg                   : Physical base address and length of the controller's registers.
- interrupts            : The interrupt outputs from the controller.
- #gpio-cells           : Should be two:
                            The first cell is the pin number.
                            The second cell is used to specify optional parameters:
                              - bits[3:0] trigger type and level flags:
                                  1 = low-to-high edge triggered.
                                  2 = high-to-low edge triggered.
                                  4 = active high level-sensitive.
                                  8 = active low level-sensitive.
- gpio-controller       : Marks the device node as a GPIO controller.
- interrupt-controller  : Marks the device node as an interrupt controller.
- gpio-bank             : Specifies which bank a controller owns.
- st,supports-sleepmode : Specifies whether controller can sleep or not

Example:

                gpio1: gpio@8012e080 {
                        compatible = "st,nomadik-gpio";
                        reg =  <0x8012e080 0x80>;
                        interrupts = <0 120 0x4>;
                        #gpio-cells = <2>;
                        gpio-controller;
                        interrupt-controller;
                        st,supports-sleepmode;
                        gpio-bank = <1>;
                };